The present invention relates generally to an inner sole structure for a sports shoe, and more particularly, to an improvement in the structure for enhancing a cushioning ability, stability and durability, and reducing weight.
Various efforts have been made to enhance cushioning ability of a sock liner in order to improve cushioning properties of an entire sole structure of sports shoes. The most effective way to enhance cushioning ability of the sock liner is form the sock liner of a soft material. However, in this case, when a shoe strikes onto the ground a portion of the sock liner sinks excessively, which may decrease stability at the time of striking onto the ground. Also, by using a soft material the sock liner may easily lose its elasticity and durability may decrease.
A sock liner or an inner sole structure for a shoe as shown in Japanese patent application laying-open publication No. 2004-313774 has been proposed to secure cushioning ability, prevent an excessive sinking of the sock liner, and improve durability. The sock liner structure is composed of an upper liner formed of a soft elastic member, a lower liner disposed under the upper liner and formed of a soft elastic member, and a wavy sheet interposed between the upper liner and the lower liner and having wavy corrugations.
When the shoe strikes onto the ground the upper and lower liners of soft elastic members absorb an impact load to secure cushioning properties, and the wavy sheet interposed between the upper and lower liners restrains deformation of the upper and lower liners to prevent the upper and lower liners from sinking excessively. Also, in this case, since the disposition of the wavy sheet restrains the amount of deformation of the upper and lower liners thus decreasing loss of elasticity of the upper and lower liners to improve durability.
However, in this case, because the upper and lower liners formed of soft elastic members are disposed at the upper and lower positions of the wavy sheet, the entire sock liner structure becomes heavy.
An object of the present invention is to provide an inner sole structure for a sports shoe that can enhance cushioning ability, stability and durability, and that can reduce weight of the structure.
Other objects and advantages of the present invention will be obvious and appear hereinafter.